NIEHS is leading a National Institutes of Health (NIH) long term study looking at the potential health effects of the Deepwater Horizon oil spill in various responder populations. During FY 2016, the GuLF STUDY (Gulf Long-term Follow-Up Study) actively conducted follow-up interviews with participants (approximately 2 years after they enrolled). Additionally, we invited 6,200 English-speaking cohort members living within 60 miles of clinics in New Orleans, LA or Mobile, AL to take part in clinical examinations. A total 3,400 participated, in hopes of completing exams. Participants underwent comprehensive lung function testing and completed a battery of behavioral and physiological tests to assess neurological function. Biological samples were collected to assess immune, renal, and kidney function and to allow for longitudinal comparisons for the subset of persons who provided samples at an earlier home visit and at the clinic. Smaller clinical sub-studies, such as assessing temporal changes in stress hormones through collection of repeat saliva samples, were also included. Finally, participants completed a comprehensive clinical mental health assessment which included questionnaire modules to assess traumatic events and substance abuse as well as questions designed to assess mental health services utilization by participants. In the meantime, NIEHS investigators are working to evaluate all of the available environmental and occupational exposure monitoring data in order to more completely characterize exposures in the study population. An ordinal job-exposure matrix was developed that characterizes exposure to total hydrocarbons as a marker for oil spill experiences. Questionnaire data were used to characterize exposure to toxicants associated with burning oil and to dispersants. A manuscript has been submitted for publication and preliminary exposure-outcome papers are being drafted using these exposure metrics and data self-reported at the enrollment telephone interview. Ongoing statistical modeling will lead to the development of chemical specific, time dependent job-exposure metrics, e.g. for the BTEX chemicals and other exposures related to oil spill cleanup. Spatial models are being developed to account for exposure to PM2.5, and to account for small-area neighborhood features such as socioeconomic factors or crime statistics within a county or at the census tract level. Approaches and preliminary results from exposure characterization efforts were presented at national and international meetings and workshops. Ongoing analysis of baseline data is focusing on mental health, pulmonary function, cardiovascular outcomes, respiratory health and a range of specific and non-specific symptoms reported by participants while working on the response and clean-up. A paper describing the cohort and methods used has been preliminarily accepted for publication. A paper describing the GuLF STUDY biorepository and how to access samples has been submitted for publication as has a paper describing the ordinal exposure metrics. Published papers describe statistical methods used in developing exposure measures for participants based on environmental sampling data from the time of the spill and questionnaire responses. Papers have also described the impact of access to care on on reporting of mental health symptoms and the impact of how physical health symptoms contribute to workers risk for mental health symptoms.